Silicone polyamide copolymers have found widespread use in various commercial formulations. In particular, silicone polyamide copolymers have found utility in personal care formulations for their ability to act as a “structuring” or “gelling” agent in a composition containing a silicone, especially volatile silicones. The following summarizes representative examples of such patent references.
U.S. Pat. No. 5,874,069 teaches a base composition and corresponding cosmetic composition which can be formed as solids (for example, gels or sticks) and which comprise a solvent which includes a silicone fluid (for example, a silicone oil such as cyclomethicone) and a thickening agent formed from a wax and a polyamide gellant wherein at least one of the wax and polyamide includes silicon-containing moieties.
U.S. Pat. No. 5,919,441 discloses compositions which comprises gelling agents which (1) contain both siloxane groups and hydrogen-bonding groups to thicken compositions containing silicone fluids (volatile and/or non-volatile silicone fluids); (2) are non-flowable solids at room temperature; and (3) dissolve in a fluid which contains silicone at a temperature of 25-250° C. to form a translucent or clear solution at a temperature in this range.
U.S. Pat. No. 6,051,216 disclose siloxane-based polyamides as gelling agents for cosmetic products, methods for making such agents, formulations thereof and cosmetic formulations therewith. The polyamides according to the '216 patent contain siloxane groups in the main chain and act to thicken compositions containing volatile and/or non-volatile silicone fluids.
While these references represent advances in the art, a need still exists for improved gelling agents. In particular there is a need to identify silicone based gelling or structuring agents for volatile siloxane based formulations where the silicone gelling agent is not as brittle as the silicone polyamide known in the art. There is also a need to identify silicone gelling agents having lower melt temperatures than the silicone polyamides known in the art, for improved personal care formulations. Furthermore, there is a need to identify improved silicone polyamide structuring/gelling agents have improved hydrophilicity which can allow improved formulation flexibility with polar solvents.
The present inventors have discovered certain silicone block copolymers containing polyether-amide units that solve the aforementioned needs.